Prenatal diagnosis of trisomy 9. Six cases and a review of the literature.

Six prenatally diagnosed cases of trisomy 9 are reported and 22 previously reported cases are reviewed; the difficulty of genetic counselling for such cases and the variation in the percentage of trisomic cells in different tissues, thus making accurate diagnosis of trisomy 9 difficult, are emphasized. In addition to karyotyping results, ultrasound findings are important in achieving diagnoses. Finally, a course of action when prenatal trisomy 9 is detected is proposed.

[Monosomy 4 p-- (Wolf-Hirschorn's syndrome)].

The phenotype of the 4 p-- syndrome may be clinically distinguished from the one of the 5 p-- syndrome by the presence of fusion abnormalities of the median line. In the case reported, these abnormalities concerned a cleft palate, an iris coloboma and a fistula of the sacrum, in addition to an important hypotrophy and a severe mental retardation associated with epilepsy.

Production of C and T bands in human mitotic chromosomes after heat treatment.

A modified thermal denaturation of human chromosomes in Hanks' solution at 91 degrees C produces highly contrasted C and T bands. This improved double-banding system is a good tool in the analysis of ring chromosomes, for which R banding is often inadequate, as it is exemplified.